Stents of this kind are used to protect against collapse or occlusion of channels in living bodies, for example blood vessels, esophagus, urethra or renal ducts, by expansion of their tubular bridge structure inside the channel. They also serve as carriers for medicaments in channels of the body and thus permit local therapy inside the channel.
The bridge structure of such stents is composed of a large number of bridges that are in each case connected to one another at node regions and delimit individual cells arranged alongside one another. By widening of the individual cells, the bridge structure as a whole can be expanded, and in some stents, can also be reduced in size again by making the cells smaller. The bridges thus form connection elements between the node regions that are substantially stiff and make a large contribution to the supporting action of a stent.
To ensure that the stent bears on the channel wall, it has to be able to expand radially in the channel. Additionally, in the expanded state, the stent must be able to fulfill its support function. The aim, therefore, is to design a stent optimally in terms of its deformation behavior and in terms of the resulting elongation and stress.